Geometric isomerism of layered complexes of uranyl selenates: Synthesis and structure of (H3O)[C5H14N]2[(UO2)3(SeO4)4(HSeO4)(H2O)] and (H3O)[C5H14N]2[(UO2)3(SeO4)4(HSeO4)(H2O)](H2O)

Abstract

New uranyl selenates with organic cations (H3O)[C5H14N]2[(UO2)3(SeO4)4(HSeO4)(H2O)] (I) and (H3O)[C5H14N]2[(UO2)3(SeO4)4(HSeO4)(H2O)](H2O) (II) were synthesized by evaporation of aqueous solutions and studied. Compound I has monoclinic symmetry, space group C2/c, a = 16.7572(13), b = 11.7239(12), c = 19.0490(13) A, β = 98.875(6)°, V = 3697.6(5) A3, Z = 4. The crystal structure was solved by the direct method and refined to R 1 = 0.085 for 2868 reflections with |F hkl | ≥ 4σ|F hkl |. Compound II has monoclinic symmetry, space group P21/n, a = 10.8252(10), b = 19.0007(10), c = 18.6463(15) A, β = 100.324(7)°, V = 3773.2(5) A3, Z = 4. The crystal structure was solved by the direct method and refined to R 1 = 0.084 for 5721 reflections with |F hkl | ≥ 4σ|F khl |. The structures of I and II are based on layered complexes [(UO2)3(SeO4)4(HSeO4)(H2O)]3− formed by combination of uranyl pentagonal bipyramids and selenate tetrahedra. H3O+ cations, water molecules, and protonated methylbutylamine cations are located in the interlayer space. Geometric isomerism of two-dimensional complexes [(UO2)3(SeO4)5(H2O)] in the structures of uranyl selenates was found and described.